+/* vi: set sw=4 ts=4: */
/* clientpacket.c
*
* Packet generation and dispatching functions for the DHCP client.
*
* Russ Dill <Russ.Dill@asu.edu> July 2001
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
-
-#include <string.h>
-#include <sys/socket.h>
+
#include <features.h>
-#if __GLIBC__ >=2 && __GLIBC_MINOR >= 1
+#if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined _NEWLIB_VERSION
#include <netpacket/packet.h>
#include <net/ethernet.h>
#else
#include <linux/if_packet.h>
#include <linux/if_ether.h>
#endif
-#include <stdlib.h>
-#include <time.h>
-#include <unistd.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-#include <errno.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-
+#include "common.h"
#include "dhcpd.h"
-#include "packet.h"
-#include "options.h"
#include "dhcpc.h"
-#include "debug.h"
+#include "options.h"
/* Create a random xid */
-unsigned long random_xid(void)
+uint32_t FAST_FUNC random_xid(void)
{
- static int initialized;
+ static smallint initialized;
+
if (!initialized) {
- int fd;
- unsigned long seed;
-
- fd = open("/dev/urandom", 0);
- if (fd < 0 || read(fd, &seed, sizeof(seed)) < 0) {
- LOG(LOG_WARNING, "Could not load seed from /dev/urandom: %s",
- strerror(errno));
- seed = time(0);
- }
- if (fd >= 0) close(fd);
- srand(seed);
- initialized++;
+ srand(monotonic_us());
+ initialized = 1;
}
return rand();
}
-/* initialize a packet with the proper defaults */
-static void init_packet(struct dhcpMessage *packet, char type)
+/* Initialize the packet with the proper defaults */
+static void init_packet(struct dhcp_packet *packet, char type)
{
- struct vendor {
- char vendor, length;
- char str[sizeof("udhcp "VERSION)];
- } vendor_id = { DHCP_VENDOR, sizeof("udhcp "VERSION) - 1, "udhcp "VERSION};
-
- init_header(packet, type);
- memcpy(packet->chaddr, client_config.arp, 6);
- add_option_string(packet->options, client_config.clientid);
- if (client_config.hostname) add_option_string(packet->options, client_config.hostname);
- add_option_string(packet->options, (unsigned char *) &vendor_id);
+ udhcp_init_header(packet, type);
+ memcpy(packet->chaddr, client_config.client_mac, 6);
+ if (client_config.clientid)
+ add_option_string(packet->options, client_config.clientid);
+ if (client_config.hostname)
+ add_option_string(packet->options, client_config.hostname);
+ if (client_config.fqdn)
+ add_option_string(packet->options, client_config.fqdn);
+ if ((type != DHCPDECLINE) && (type != DHCPRELEASE))
+ add_option_string(packet->options, client_config.vendorclass);
}
-/* Add a paramater request list for stubborn DHCP servers. Pull the data
+/* Add a parameter request list for stubborn DHCP servers. Pull the data
* from the struct in options.c. Don't do bounds checking here because it
* goes towards the head of the packet. */
-static void add_requests(struct dhcpMessage *packet)
+static void add_param_req_option(struct dhcp_packet *packet)
{
+ uint8_t c;
int end = end_option(packet->options);
int i, len = 0;
- packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
- for (i = 0; options[i].code; i++)
- if (options[i].flags & OPTION_REQ)
- packet->options[end + OPT_DATA + len++] = options[i].code;
- packet->options[end + OPT_LEN] = len;
- packet->options[end + OPT_DATA + len] = DHCP_END;
+ for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
+ if (((dhcp_options[i].flags & OPTION_REQ)
+ && !client_config.no_default_options)
+ || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
+ ) {
+ packet->options[end + OPT_DATA + len] = c;
+ len++;
+ }
+ }
+ if (len) {
+ packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
+ packet->options[end + OPT_LEN] = len;
+ packet->options[end + OPT_DATA + len] = DHCP_END;
+ }
+}
+/* RFC 2131
+ * 4.4.4 Use of broadcast and unicast
+ *
+ * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
+ * messages, unless the client knows the address of a DHCP server.
+ * The client unicasts DHCPRELEASE messages to the server. Because
+ * the client is declining the use of the IP address supplied by the server,
+ * the client broadcasts DHCPDECLINE messages.
+ *
+ * When the DHCP client knows the address of a DHCP server, in either
+ * INIT or REBOOTING state, the client may use that address
+ * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
+ * The client may also use unicast to send DHCPINFORM messages
+ * to a known DHCP server. If the client receives no response to DHCP
+ * messages sent to the IP address of a known DHCP server, the DHCP
+ * client reverts to using the IP broadcast address.
+ */
+
+static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
+{
+ return udhcp_send_raw_packet(packet,
+ /*src*/ INADDR_ANY, CLIENT_PORT,
+ /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
+ client_config.ifindex);
}
+#if ENABLE_FEATURE_UDHCPC_ARPING
+/* Broadcast a DHCP decline message */
+int FAST_FUNC send_decline(uint32_t xid, uint32_t server, uint32_t requested)
+{
+ struct dhcp_packet packet;
+
+ init_packet(&packet, DHCPDECLINE);
+ packet.xid = xid;
+ add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
+ add_simple_option(packet.options, DHCP_SERVER_ID, server);
+
+ bb_info_msg("Sending decline...");
+
+ return raw_bcast_from_client_config_ifindex(&packet);
+}
+#endif
+
+
/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
-int send_discover(unsigned long xid, unsigned long requested)
+int FAST_FUNC send_discover(uint32_t xid, uint32_t requested)
{
- struct dhcpMessage packet;
+ struct dhcp_packet packet;
init_packet(&packet, DHCPDISCOVER);
packet.xid = xid;
if (requested)
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
- add_requests(&packet);
- LOG(LOG_DEBUG, "Sending discover...");
- return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
- SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
+ /* Explicitly saying that we want RFC-compliant packets helps
+ * some buggy DHCP servers to NOT send bigger packets */
+ add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
+
+ add_param_req_option(&packet);
+
+ bb_info_msg("Sending discover...");
+ return raw_bcast_from_client_config_ifindex(&packet);
}
-/* Broadcasts a DHCP request message */
-int send_selecting(unsigned long xid, unsigned long server, unsigned long requested)
+/* Broadcast a DHCP request message */
+/* RFC 2131 3.1 paragraph 3:
+ * "The client _broadcasts_ a DHCPREQUEST message..."
+ */
+int FAST_FUNC send_select(uint32_t xid, uint32_t server, uint32_t requested)
{
- struct dhcpMessage packet;
+ struct dhcp_packet packet;
struct in_addr addr;
init_packet(&packet, DHCPREQUEST);
add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
add_simple_option(packet.options, DHCP_SERVER_ID, server);
-
- add_requests(&packet);
+ add_param_req_option(&packet);
+
addr.s_addr = requested;
- LOG(LOG_DEBUG, "Sending select for %s...", inet_ntoa(addr));
- return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
- SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
+ bb_info_msg("Sending select for %s...", inet_ntoa(addr));
+ return raw_bcast_from_client_config_ifindex(&packet);
}
/* Unicasts or broadcasts a DHCP renew message */
-int send_renew(unsigned long xid, unsigned long server, unsigned long ciaddr)
+int FAST_FUNC send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
{
- struct dhcpMessage packet;
- int ret = 0;
+ struct dhcp_packet packet;
init_packet(&packet, DHCPREQUEST);
packet.xid = xid;
packet.ciaddr = ciaddr;
- add_requests(&packet);
- LOG(LOG_DEBUG, "Sending renew...");
- if (server)
- ret = kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
- else ret = raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
- SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
- return ret;
-}
+ add_param_req_option(&packet);
+ bb_info_msg("Sending renew...");
+ if (server)
+ return udhcp_send_kernel_packet(&packet,
+ ciaddr, CLIENT_PORT,
+ server, SERVER_PORT);
+
+ return raw_bcast_from_client_config_ifindex(&packet);
+}
/* Unicasts a DHCP release message */
-int send_release(unsigned long server, unsigned long ciaddr)
+int FAST_FUNC send_release(uint32_t server, uint32_t ciaddr)
{
- struct dhcpMessage packet;
+ struct dhcp_packet packet;
init_packet(&packet, DHCPRELEASE);
packet.xid = random_xid();
packet.ciaddr = ciaddr;
-
- add_simple_option(packet.options, DHCP_REQUESTED_IP, ciaddr);
+
add_simple_option(packet.options, DHCP_SERVER_ID, server);
- LOG(LOG_DEBUG, "Sending release...");
- return kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
+ bb_info_msg("Sending release...");
+ return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
}
-/* return -1 on errors that are fatal for the socket, -2 for those that aren't */
-int get_raw_packet(struct dhcpMessage *payload, int fd)
+/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
+int FAST_FUNC udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
{
int bytes;
- struct udp_dhcp_packet packet;
- u_int32_t source, dest;
- u_int16_t check;
+ struct ip_udp_dhcp_packet packet;
+ uint16_t check;
- memset(&packet, 0, sizeof(struct udp_dhcp_packet));
- bytes = read(fd, &packet, sizeof(struct udp_dhcp_packet));
+ memset(&packet, 0, sizeof(packet));
+ bytes = safe_read(fd, &packet, sizeof(packet));
if (bytes < 0) {
- DEBUG(LOG_INFO, "couldn't read on raw listening socket -- ignoring");
- usleep(500000); /* possible down interface, looping condition */
- return -1;
+ log1("Packet read error, ignoring");
+ /* NB: possible down interface, etc. Caller should pause. */
+ return bytes; /* returns -1 */
}
-
- if (bytes < (int) (sizeof(struct iphdr) + sizeof(struct udphdr))) {
- DEBUG(LOG_INFO, "message too short, ignoring");
+
+ if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
+ log1("Packet is too short, ignoring");
return -2;
}
-
+
if (bytes < ntohs(packet.ip.tot_len)) {
- DEBUG(LOG_INFO, "Truncated packet");
+ /* packet is bigger than sizeof(packet), we did partial read */
+ log1("Oversized packet, ignoring");
return -2;
}
-
+
/* ignore any extra garbage bytes */
bytes = ntohs(packet.ip.tot_len);
-
- /* Make sure its the right packet for us, and that it passes sanity checks */
- if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION ||
- packet.ip.ihl != sizeof(packet.ip) >> 2 || packet.udp.dest != htons(CLIENT_PORT) ||
- bytes > (int) sizeof(struct udp_dhcp_packet) ||
- ntohs(packet.udp.len) != (short) (bytes - sizeof(packet.ip))) {
- DEBUG(LOG_INFO, "unrelated/bogus packet");
- return -2;
+
+ /* make sure its the right packet for us, and that it passes sanity checks */
+ if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
+ || packet.ip.ihl != (sizeof(packet.ip) >> 2)
+ || packet.udp.dest != htons(CLIENT_PORT)
+ /* || bytes > (int) sizeof(packet) - can't happen */
+ || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
+ ) {
+ log1("Unrelated/bogus packet, ignoring");
+ return -2;
}
- /* check IP checksum */
+ /* verify IP checksum */
check = packet.ip.check;
packet.ip.check = 0;
- if (check != checksum(&(packet.ip), sizeof(packet.ip))) {
- DEBUG(LOG_INFO, "bad IP header checksum, ignoring");
- return -1;
+ if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
+ log1("Bad IP header checksum, ignoring");
+ return -2;
}
-
- /* verify the UDP checksum by replacing the header with a psuedo header */
- source = packet.ip.saddr;
- dest = packet.ip.daddr;
+
+ /* verify UDP checksum. IP header has to be modified for this */
+ memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
+ /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
+ packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
check = packet.udp.check;
packet.udp.check = 0;
- memset(&packet.ip, 0, sizeof(packet.ip));
-
- packet.ip.protocol = IPPROTO_UDP;
- packet.ip.saddr = source;
- packet.ip.daddr = dest;
- packet.ip.tot_len = packet.udp.len; /* cheat on the psuedo-header */
- if (check && check != checksum(&packet, bytes)) {
- DEBUG(LOG_ERR, "packet with bad UDP checksum received, ignoring");
+ if (check && check != udhcp_checksum(&packet, bytes)) {
+ log1("Packet with bad UDP checksum received, ignoring");
return -2;
}
-
- memcpy(payload, &(packet.data), bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
-
- if (ntohl(payload->cookie) != DHCP_MAGIC) {
- LOG(LOG_ERR, "received bogus message (bad magic) -- ignoring");
+
+ memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
+
+ if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
+ bb_info_msg("Packet with bad magic, ignoring");
return -2;
}
- DEBUG(LOG_INFO, "oooooh!!! got some!");
+ log1("Got valid DHCP packet");
+ udhcp_dump_packet(dhcp_pkt);
return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
-
}
-
projects / oweals / busybox.git / blobdiff